The following description sets forth the inventors' knowledge of related art and problems therein and should not be construed as an admission of knowledge in the prior art.
In a semiconductor production apparatus or inspection apparatus (hereinafter collectively referred to as “semiconductor production apparatus”), a substrate transferring robot has been conventionally used to transfer a substrate, such as, e.g., a semiconductor wafer, to a given position. The substrate transferring robot is equipped with a retractable arm having, at its tip end, a substrate mounting portion called “hand fork,” “fork,” or “end effector” (hereinafter referred to as “hand”). The substrate is transferred to a given position with the substrate mounted on the hand.
On the other hand, for the purpose of improving the yield ratio in a semiconductor production, it has been required that minute particles do not adhere to a substrate in the production steps.
Under the circumstances, in a recent substrate transferring robot, a hand configured to hold only a peripheral portion of a substrate has been used (see Japanese Unexamined Laid-open Patent Publication No. 2002-170862, hereinafter referred to as “Patent Document 1”). This hand is called “edge grip hand” or the like. This hand is configured to make physical contact with only a peripheral portion of a substrate, which causes less adherence of particles of the hand to a substrate. This edge grip hand described in Patent Document 1 has a first contact portion which comes into contact with a periphery of a substrate at the side of the substrate to be attached to a base of the hand of a substrate transferring robot, and second and third contact portions which come into contact with the substrate at the opposite side of the substrate, extended from the base. The second and third contact portions (holding claws) are driven by a driving means equipped on the base of the hand, so that the substrate is held by the first to third contact portions.
The hand as described in Patent Document 1 has the following problems.
The first problem is that the structure is large in planar size and weight of the hand itself. In detail, as described above, the hand disclosed by Patent Document 1 has a first contact portion which comes into contact with a periphery of a substrate on one side of the substrate, second and third contact portions which come into contact with the substrate on the other side of the substrate. Therefore, the length from the first contact portion to the second and third contact portions is required to have at least a size larger than the diameter of the substrate to be held by the hand. This increases the planar size of the hand, which in turn increases the weight of the hand. The hand large in size and weight increases the load and moment of the arm of the substrate transferring robot, which in turn causes deterioration of the arm positional accuracy.
The next problem is that the structure increases the thickness of the hand itself. The hand described in Patent Document 1 is equipped with driving means for realizing the holding operation for holding the sides of the substrate, and a number of parts driven by the driving means to perform the holding operation. This increases the thickness of the hand, which in turn requires increasing of the size of the opening through which the substrates passes when transferring in accordance with the thickness of the hand.
Another problem is that it is hard to invert or stand up the hand. In a semiconductor production apparatus, in some cases, the substrate transferring robot is required to turn over a substrate to, e.g., wash or polish it. Also, in some cases, it is required to transfer a substrate in a state in which the hand of the substrate transferring robot holding the substrate is in an upright position (i.e., in a vertically raised position). To cope with such requests, in some substrate transferring robots, an inversion mechanism for inverting a hand or a standing mechanism for vertically standing a hand is equipped at the tip end portion of the arm. In the hand as described in Patent Document 1, however, since the size and weight of the hand are large, the aforementioned mechanism becomes large. Furthermore, since it is required to inverse the hand large in planar size, the three-dimensional size required for the inversion and/or standing operation becomes large.
Still another problem is that the configuration of the substrate transferred side is limited. In detail, the hand as described in Patent Document 1 is formed into a two-pronged shape extended from the base of the hand. This requires that the configuration of the substrate transferred size (i.e., the side of receiving the substrate) is formed so as to avoid the two-pronged portion of the hand.
The description herein of advantages and disadvantages of various features, embodiments, methods, and apparatus disclosed in other publications is in no way intended to limit the present invention. Indeed, certain features of the invention may be capable of overcoming certain disadvantages, while still retaining some or all of the features, embodiments, methods, and apparatus disclosed therein.